Low-Molecular-Weight Heparin: From the Bench to the Orthopedic Patient

Standard heparin is widely used for the prevention and treatment of venous thromboembolism; however, it has several limitations including variable dose response, dose-dependent clearance and inhibition of platelet function. To overcome these disadvantages, standard heparin, which is composed of glycosaminoglycans of various molecular weights, has been fractionated into its low-molecular-weight component. Low-molecular-weight heparin (LMWH) exhibits less binding to plasma proteins and endothelial cells than standard heparin resulting in a more predictable dose response profile, a dose-independent mechanism of clearance and a longer plasma half-life. LMWH also has a lower binding affinity for platelets and produces less microvascular bleeding. Evidence from randomized clinical trials demonstrates that LMWH is effective in the prevention of deep vein thrombosis (DVT) in high-risk orthopedic patients. There is also considerable evidence of its efficacy and safety in the initial treatment of proximal DVT. Recent studies have demonstrated the feasibility of home treatment with LMWH, which offers the advantage of greater clinical utility compared with current antithrombotic regimens and hence the possibility of cost savings.